The present invention relates to a process for the production of a palatability enhancing autolysate from a filamentous fungal biomass.
The autolysis of the various cells is a well recognized phenomenon, and occurs when the endogenous enzymes contained in cells, such as proteases and nucleases digest the components of the cell. Autolysis solubilizes the various degradation products of the cell, including amino acids, peptides, or nucleotides to provide a "self digestion" process for the cell. Yeast autolysis for example has provided a means for the hydrolysis of yeast to result in a variety of autolyzed cellular components which can be used as a seasoning or flavoring for the preparation of sauces, gravies, soups or other materials. The autolysis of yeast, however, is generally a slow reaction and can take as long as several days to obtain a suitable degree of digestion. It is for this reason, that various additives have been proposed for stimulating or accelerating the autolysis of yeast.
U.S. Pat. No. 4,285,976 for example, describes an autolysis process for yeast that is accelerated by the addition of thiamine or pyridoxine and a gradual increase in temperature of the slurry. U.S. Pat. No. 4,218,481 also describes a process in which yeast autolysis is enhanced by the addition of proteases to improve the yield and shorten the time required for autolysis. In spite of the above improvements, these procedures are dependent upon the addition of an autolytic initiator to begin the autolysis process. Typically these materials are plasmolyzing or liquefying agents such as salt and organic solvents which appear to dissolve or solubilize lipophilic substances in the cell thereby permitting the endogenous enzymes to initiate autolysis or destruction of the cell components.
While extensive studies have been carried out relative to the autolysis of yeast, little work has been completed insofar as the autolysis of other types of fungal protein, particularly those derived from the growth or reproduction of filamentous fungi. The class of fungi that is identified as filamentous generally refers to that group of fungi having hyphae or mycelium as contrasted with yeast which lacks this characteristic filamentous structure. Typical filamentous fungi include those of the genus Rhizopus and Aspergillus which have for years been used in the production of fermented food products in the Far East. Typical products produced by these fungi include "Tempeh" which is an Indonesian food grown on cracked soybeans, as well as other pastes and sauces used in Japan and China, such as soy sauce, shoyu and miso. These foods have all been developed from the fermentation of various substrates with Aspergillus or Rhizopus fungi.
Although the autolysis of various fungi such as A. oryzae and A. niger has been studied for example in Agriculture Biology Chemistry: Vol 29, p. 1033-1041 (1965) and in Noka; 51(8), p 25-81 (1977); these studies have still required an initiator, such as ethyl acetate to initiate or induce autolysis of the organism. These studies also had the expectation of possibly producing effective flavor components from the autolysis, however, it was found that pleasantly flavored components did not result. The autolysis of filamentous fungi for the production of palatability enhancing materials has therefore been unsuccessful up to the present time.
The production of desirable palatability enhancing materials from the autolysis of filamentous fungi and biomasses produced therewith, has been unexpectedly achieved in the present invention.
It is therefore an object of the present invention to provide a process for the autolysis of filamentous fungi to produce palatability enhancing materials.
It is a further object of the present invention to provide a process for autolysis of biomasses produced by the growth of filamentous fungi to produce palatability enhancing materials.
It is a still further object of the present invention to provide a procedure for the autolysis of filamentous fungi that is self starting without the need for an added autolysis stimulator or initiator.
It is a further object of the present invention to provide a process for the autolysis of filamentous fungi that is rapid, and provides a relatively high yield of palatability enhancing materials.
It is a further object of the present invention to provide a reliable procedure for the autolysis of filamentous fungi with a high yield of materials that enhance the palatability of animal foods, particularly pet foods.
These and other objects of the present invention will be readily apparent from the following specific description.